Our editors pick the products & services we write about. When you buy through our links, we may get a commission. Learn more.

How to Install a Car Battery

Knowing how to install a car battery in the comfort of your home garage saves you the time, money, and hassle of a trip to the mechanic. It’s one of the easiest car repairs you can make, too. You can even install a kill switch when you’re doing it so that you can prevent potential thieves from driving off with your car.

Want to know more? We’ll walk you through the whole process below, along with giving you some helpful tips for installing your new battery safely!

How Do You Know If You Need a New Battery?

The answer to this question might seem obvious. If your battery is dead, your car won’t start. A dead battery isn’t the only thing that can prevent your car from starting, though—and there are other signs that tell you it’s time for a new battery before it dies completely. 

how to install a car battery
Knowing how to install a car battery will make your life much easier

Your check engine light may come on if your battery is weak. Some cars have a battery light on the dash, as well. Other signs it’s time for a new battery include:

  • Sluggish engine cranking or failure to crank
  • Dim or failing headlights or dash lights
  • Bloating or swelling of the battery housing
  • Battery acid leaks or drips

If your car won’t start and you want to confirm the battery is the cause, your best bet is to use a multimeter to check the voltage. A healthy battery should have a voltage around 12.6 volts. If the voltage is less than 10, your battery either needs to be replaced or reconditioned. 

How to Install a Car Battery: Step by Step

  1. Before you buy the new battery, inspect the terminals of the current battery for corrosion. Corrosion on the terminals can interrupt the flow of electricity, preventing a battery from providing power even if it’s otherwise healthy. If you see corrosion, clean it away using a toothbrush dipped in a mix of 1 tablespoon baking soda dissolved in 1 cup of hot water. 
  2. Check the voltage, chemistry, and capacity of your current battery. This information should be printed on the label. If you can’t find or can’t read the label, it should also be in your vehicle’s manual. When you buy the new battery, make sure it matches these specifications to avoid electrical problems. 
  3. Make sure your car’s engine is off and the keys are removed from the ignition. 
  4. Remove the negative cable from the battery. This will usually be black and marked with a minus sign (-). Most cables can be removed easily by twisting and pulling up. If it won’t come off, you may want to purchase a battery puller, which will help you remove the cable without damaging the terminal.
  5. Remove the positive cable from the battery using the same method in step 3. This will often be red and marked with a plus sign (+).
  6. Take off any clamps or braces holding the battery in place. Depending on your vehicle, you may need a ratchet, wrench, or socket set. Set the parts aside somewhere they won’t be disturbed or lost.
  7. Lift the old battery from the tray and set it aside on a flat surface. 
  8. Place the new battery in the tray and secure it with the brace or clamp you removed in step 6.
  9. Attach and tighten the positive cable first, followed by the negative cable. Ensure all the connections and holds are secure before closing the hood.

Safety Tips For Installing Car Batteries

Knowing how to install a car battery safely is important for both your health and the health of your battery and engine. Keep these tips in mind and you’ll be sure to install your battery without incident. 

  • Always remove the negative cable first, and reconnect it last. This will prevent sparks that could damage the battery or injure you.
  • When you remove the old battery, grab from the bottom, and use both hands. Batteries are surprisingly heavy, and this will prevent you from dropping it or straining your joints. Some batteries come with handles, which is the best way to remove the battery if it’s there.
  • Wear gloves and eye protection if handling a battery that’s bloated, swelling, cracked, or leaking. Battery acid is highly corrosive and can injure you if it comes into contact with your skin. 
  • Work in a well-ventilated area to avoid build-up of gasses that can cause sparks and explosions.
  • Keep all batteries (even dead batteries) away from open flames, cigarettes, and high heat.

How to Install a Killswitch on a Car Battery

A kill switch on a battery is an anti-theft device that allows you to shut off the flow of electricity from your ignition with the push of a button. While there are a variety of options for kill switches, the easiest ones to install tend to be those on the battery.

When you’re buying a battery kill switch, first look at your vehicle’s manual and find the power output of the battery and electrical system. Make sure the kill switch you buy matches this amount. If it doesn’t, you could blow out the kill switch.

You can have a kill switch installed by a mechanic, but it’s an easy enough upgrade to make at home in your own garage. Doing so usually only takes an hour or less. Here’s how you do it:

  1. Disconnect both the positive and the negative cables.  
  2. Unscrew the positive cable from the battery terminal. 
  3. Install the kill switch between the cable and battery terminal on the positive side of the battery. Make sure the switch is in the “on” position when you install it.
  4. Reconnect the positive battery terminal. It should be tight, but not so tight that it damages the wires. 
  5. Now that the wires are connected to the battery, you just need to put the housing for the switch on your car frame. It’s best to put it somewhere that’s hidden so any potential thieves can’t locate it easily.
  6. Mark the location for the installation screws first to make sure you’re placing them correctly. Drill the holes and wipe away any shavings or scraps that are created as a result. 
  7. Line up the holes on the kill switch housing with those you just drilled and secure it in place with screws. You can use silicone caulking to weather-proof the wire connectors and prevent corrosion or other damage. 
  8. After the kill switch is completely installed, you can re-connect the battery cables. 

The Final Word

As long as you follow the right precautions, installing a new battery is a simple and safe process to do at home. We hope the advice in this article has given you the confidence and knowledge you need to replace your car’s battery!

Bonus: Check out our guide on how to change a watch battery!

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top